Electrically-heated kiln



Sept. 23, 1930.

B. J. MOORE ET AL ELECTRI GALLY HEATED KILN Filed Nov. 26, 1927 FIGJ.

III

All

/////////////A (fl is to provide an improve I Figu Patented Sept. 23, 1930 um'rsn STATES PATENT OFFICE BERNARD JOSEPH MOORE, OF STOKI'LON-TRENT, AND ARTHUR JOHN CAMPBELL, OI

STONRfENGLAND, ASSIGNORS OF ONE-HALF T0 GIIBBONS BROTHERS LDII'I'ED, OF

DUDLEY, ENGLAND, A COMPANY OF GREAT BRITAIN ELECTBICALLYJHEATED KILN Application fled November 26, 1927. Serial No. 285,980.

This invention relates to electrically heated kilns and is particularly applicable to electrically heated kilns of the tunnel type wherein trucks containing goods are passed successively through an entrance zone, a pre-heat-' ing zone, a heating zone, and a cooling zone.

One of the objects of the present invention is to provide improved means for supporting the heating coils in such manner t at the danger of short circuiting due to expansion of the coils is avoided.

A further object of the resent invention arrangement of heating elements to obtain more uniform heating in the tunnel. 1

Referring to the drawings Figure 1 is a sectional view on line 11 of re 2 of the pre-heating or heating sections of a tunnel.

Figure 2 is a sectional plan view.

Figure 3 is a transverse section on line Figure 4 is a view upon an enlarged scale showing the heating coils.

Figure 5 is a transverse section taken throu h two of the heating coils.

In t 0 construction illustrated the kiln con-- sists of a tunnell built up of heat resisting blocks or bricks and having rails 2 at its base whereon trucks may run.

Between the heating chamber 3 of the tunnel and the railsand the chamber 4 in which the under carriage of. the trucks run is a constricted opening 5 formed by projecting ridges 6 of the brick work.

The heating coils? of resistance wire or material are hung upon knife edge rods 8 of insulating material, the coils 7 being so large in relation to the rods 8 that they touch the rods only along their top edges.

By this arrangement it is possible to work at high temperatures and as such temperatures cause expansion and distortion of the coils 7 about midway along the length of each coil and below the coil a peg 9 of insulating material is secured in the adjacent wall 10 of the kiln. The purpose of the pegs 9 is to prevent the coils 7 upon expansion or distortion or breakvided with upwardly the projections for retaining the When at high temperature the coils may expand to such a degree that those parts thereof which areadjacent to the wall 10 may come into contact with the wall. Since there can be no further'movement in this direction or downwardly owing to the egs 9 further expansion of the coils must ta e place in an outward direction. In order to prevent the coils from thus sliding the rods 8 laterally ofi the projections 11 the projections are proextending lips or flan es 12.

T e leadin in cables 13 pass into the kiln through suita 1e openings extending through the walls of the kiln from the outside.

In kilns of the type to which this invention relates difiiculty has been experienced owing to the fact that the heated ,air in the kiln rises to the top so that the upper levels of the kiln become much hotter than its lower part.

In order to overcome this difliculty we provide in the pre-heating section 14 two rows 15 of heating elements which are disposed near the base of the hot chamber.

These rows'of heatin elements exceed the heating elements 16 o the heating sectionproper in len h and com rise two thirds of the number 0 coils in the l ieating section.

/ One or more outlets such as 17 may be provided for the escape of. the heated air and such outlets may be controlled by a Valve or dam or if desired.

at we claim then is An electrically heated kiln comprising a tunnel, said tunnel having recesses in its walls, projections upon the walls of said tunnelwithin said recesses arranged in rows one above another, horizontal knife edged insulating rods carried by said projections and arranged one above another in spaced relationship, tension free coils of resistance wire wound around the insulating rods, lips upon insulating project' neath eac rods in position thereon,

and pe from the walls of the furnace resistance coil normally spaced therefrom to prevent an upper coil contacting with a coil immediately below in the event of the in sulating, rod. carrying the upper coil breakin% or the coil itself saggilgg J n witness whereof we a our signatures.

BERNARD-JOSEPH MOORE. ARTHUR JOHN CAMPBELL. 

